This section provides background information related to the present disclosure which is not necessarily prior art.
Scroll compressors are used in applications such as refrigeration systems, air conditioning systems, and heat pump systems to pressurize and, thus, circulate refrigerant within each system.
As the scroll compressor operates, an orbiting scroll member having an orbiting scroll member wrap orbits with respect to a non-orbiting scroll member having a non-orbiting scroll member wrap to make moving line contacts between flanks of the respective scroll wraps. In so doing, the orbiting scroll member and the non-orbiting scroll member cooperate to define moving, crescent-shaped pockets of vapor refrigerant. A volume of the fluid pockets decreases as the pockets move toward a center of the scroll members, thereby compressing the vapor refrigerant disposed therein from a suction pressure to a discharge pressure.
Two types of contacts define the fluid pockets formed between the orbiting scroll member and the non-orbiting scroll member, and create forces therebetween. Namely, radial or flank forces are created by axially extending tangential line contacts between spiral faces or flanks of the scroll wraps and axial forces are created by area contacts between the planar edge surfaces, or tips, of each scroll wrap and an opposing end plate of the other scroll member. While such forces are easily managed in a fixed-speed compressor, flank forces can be a source of undesirable fluid leakage and sound that is difficult to manage in a variable-speed compressor. Undesirable sound and frictional efficiency losses are experienced at higher speeds in the variable-speed compressor, particularly in radially compliant variable-speed scroll compressors. Such radially compliant scroll compressors incorporate an unloader bushing for allowing the flanks of the orbiting scroll to disengage the flanks of the non-orbiting scroll while the compressor is not in operation, and allow the flanks of the orbiting and non-orbiting scrolls to engage while in operation. Such radial compliant scroll compressors are described in U.S. Pat. No. 5,295,813.